The Los Angeles Aqueduct Simulation Model (LAASM) was developed by the Los Angeles Department of Water and Power (LADWP) as an operations and planning model for the Los Angeles Aqueduct (LAA) system. The model objective was to analyze the entire system in order to improve LAA operations and to more fully address the impacts of potential legal restrictions on their water supplies. The goal was to create a model that was to the greatest extent representative of the physical system and operated on a monthly time period over the runoff year. Simulation on a monthly time period provides valuable insight on system operations that an annual model could not. The success of the LAASM has been illustrated through the rapid adoption and application of the code to a wide range of LADWP planning and operations studies.